Uta,this is a male Vespidae, subfamily Eumeninae.It is a male because of yellow clypeus, extracted genitalia and hooked antennae.Try the subforum "Aculeate wasps and bees / Bienen und Wespen".

I have never seen a male posing like this with genitalia poked out!I have seen something vaguely similar in a tiger moth (Arctiinae) which emits pheromones, although they are not the genitalia, try an image search for "Creatonotos gangis".